DS1822-PAR_07 DALLAS [Dallas Semiconductor], DS1822-PAR_07 Datasheet - Page 10

• Manufacturer Part Number: DS1822-PAR_07
• Description: Econo 1-Wire Parasite-Power Digital Thermometer
• Manufacturer: DALLAS [Dallas Semiconductor]

WRITE SCRATCHPAD [4Eh]
This command allows the master to write three bytes of data to the DS1822-PAR’s scratchpad. The first
data byte is written into the T
register (byte 3), and the third byte is written into the configuration register (byte 4). Data must be
transmitted least significant bit first. All three bytes MUST be written before the master issues a reset, or
the data may be corrupted.
READ SCRATCHPAD [BEh]
This command allows the master to read the contents of the scratchpad. The data transfer starts with the
least significant bit of byte 0 and continues through the scratchpad until the 9
If only part of the scratchpad contents is required, the master may issue a reset to terminate reading at any
time.
COPY SCRATCHPAD [48h]
This command copies the contents of the scratchpad T
to EEPROM. If the device is being used in parasite power mode, within 10μs (max) after this command is
issued the master must enable a strong pullup on the 1-Wire bus for at least 10ms as described in the
PARASITE POWER section.
RECALL E
This command recalls the alarm trigger values (T
places the data in bytes 2, 3, and 4, respectively, in the scratchpad memory. The master device can issue
“read-time slots” (see the 1-WIRE BUS SYSTEM section) following the Recall E
DS1822-PAR will indicate the status of the recall by transmitting 0 while the recall is in progress and
1 when the recall is done. The recall operation happens automatically at power-up, so valid data is
available in the scratchpad as soon as power is applied to the device.
DS1822-PAR FUNCTION COMMAND SET Table 4
NOTES:
1. The master must enable a strong pullup on the 1-Wire bus during temperature conversions and copies
2. The master can interrupt the transmission of data at any time by issuing a reset.
3. All three bytes must be written before a reset is issued.
Convert T
Read
Scratchpad
Write
Scratchpad
Copy
Scratchpad
Recall E
Command
from the scratchpad to EEPROM. No other bus activity may take place during this time.
2
2
[B8h]
Initiates temperature
conversion.
Reads the entire scratchpad
including the CRC byte.
Writes data into scratchpad
bytes 2, 3, and 4 (T
configuration registers).
Copies T
configuration register data from
the scratchpad to EEPROM.
Recalls T
configuration register data from
EEPROM to the scratchpad.
TEMPERATURE CONVERSION COMMANDS
H
H
Description
, T
, T
H
L
L
, and
register (byte 2 of the scratchpad), the second byte is written into the T
, and
H
, T
MEMORY COMMANDS
L
, and
10 of 19
H
and T
Protocol
H
, T
BEh
4Eh
B8h
44h
48h
L
L
) and configuration data from EEPROM and
and configuration registers (bytes 2, 3, and 4)
After Command is Issued
Master transmits three data
DS1822-PAR transmits up
to 9 data bytes to master.
DS1822-PAR transmits
bytes to DS1822-PAR.
recall status to master.
1-Wire Bus Activity
th
None
None
byte (byte 8–CRC) is read.
2
command and the
DS1822-PAR
Notes
1
2
3
1
L